Question

Difficulty: MediumIndefinite Integration of Polynomial and Trigonometric Functions

If y=(12x2+6sin(2x))dxy = \int (12x^2 + 6\sin(2x)) \, dx and y=10y = 10 when x=0x = 0, what is the value of the constant of integration CC?

Answer: 13

Answer

The value of the constant of integration CC is 1313.
Integrating 12x2+6sin(2x)12x^2 + 6\sin(2x) gives y=4x33cos(2x)+Cy = 4x^3 - 3\cos(2x) + C. Substituting x=0x = 0 yields y(0)=4(0)33cos(0)+C=3+Cy(0) = 4(0)^3 - 3\cos(0) + C = -3 + C. Setting 3+C=10-3 + C = 10 and solving for CC gives C=13C = 13.

Step-by-Step Solution

1
Integrate the function with respect to xx
y=4x33cos(2x)+Cy = 4x^3 - 3\cos(2x) + C
Applying the power rule axndx=axn+1n+1\int ax^n \, dx = \frac{ax^{n+1}}{n+1} and trigonometric integration rule ksin(bx)dx=kbcos(bx)\int k\sin(bx) \, dx = -\frac{k}{b}\cos(bx).
2
Apply the initial condition x=0x = 0 and y=10y = 10
10=4(0)33cos(0)+C10 = 4(0)^3 - 3\cos(0) + C
Substituting the boundary values to solve for the specific constant of integration.
3
Evaluate trigonometric function and solve for CC
C=13C = 13
Since cos(0)=1\cos(0) = 1, the equation simplifies to 10=3+C10 = -3 + C, leading directly to C=13C = 13.

Key Concept

Indefinite Integration of Polynomial and Trigonometric Functions with Initial Conditions
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